Shadow foreign secretary Hilary Benn has dismissed the arguments for Britain to give up its nuclear weapons amid Labour infighting on the issue.
Mr Benn ridiculed the idea that other nuclear powers would throw their missiles "in the dustbin" if the UK acted unilaterally.
The comments, during a question and answer session at the Chatham House think-tank, come as Labour tries to reconcile the unilateralist stance of leader Jeremy Corbyn with strong support for renewing Trident in the parliamentary party.
The shadow cabinet has yet to decide how it will handle a looming Commons vote on renewing the deterrent.
Mr Benn said everyone was in favour of a world without nuclear weapons, but that had to be achieved through multilateral action.
"I think you get there by multilateral negotiation and not by unilateral action," he said.
"If we gave ours up I don't believe for a second that any one of the other nuclear powers in the world would say 'well if you're not going to keep yours any more we'll throw ours in the dustbin'."
Mr Benn acknowledged that the threats today were "in some respects different" from the past, but said no-one could predict what threats there would be in the future.
"The deterrent is intended to deter and I think it has succeeded in doing that," he argued.
He added: "Who fancies living in a world in which everyone else has given up their nuclear weapons and North Korea still has its?"